A modified mouthguard material which reduces transmitted forces is described. Tests showed that the inclusion of air cells in a 4 mm thick polyvinyl-acetate-polyethylene (EVA) copolymer reduced the effects of impacts of less than 10 kN when compared with a material of the same EVA composition and thickness. The EVA copolymer with air-inclusions is suitable for the construction of stock mouth-formed and vacuum-formed mouthguards. The improved elastic properties of the modified mouthguard material reduced transmitted forces by 32 per cent when compared with traditional EVA mouthguard polymers of the same thickness.